Process and apparatus for producing an endless seamed belt

ABSTRACT

A novel method and apparatus for producing an endless flexible seamed belt using templates is disclosed. A first form of the template is a mask template with a template aperture in the form of a puzzle cut pattern to be used in combination with an excimer laser. The template is placed between the excimer laser source and the belt material to be cut. As the excimer laser traverses the width of the belt, the laser forms a puzzle cut pattern on the belt. A second form of the template is a punch and die having patterned edges in the form of a puzzle cut pattern with extremely small nodes and kerfs. The cutting tolerances of the patterned edges make it necessary to fix the punch with respect to the die so that there is no misalignment of the punch and die between cutting operations. This is accomplished by resiliently fixing the punch to the die, rather than having the punch attached to the force generating assembly as in normal punch and die assemblies. Belt material is positioned between a stock gap between the punch and die and the force generating assembly is activated to provide the cutting force. Once the belt material is cut, the cutting force is removed and the force generating assembly returns to its retracted position. Both types of templates result in very clean cuts without deformation or distortion.

This application is a division of application Ser. No. 09/493,445, filedJan. 28, 2000, now U.S. Pat. No. 6,318,223, which is a division ofapplication Ser. No. 09/004,636, filed Jan. 8, 1998, now abandoned.

CROSS REFERENCE TO RELATED APPLICATIONS

Attention is hereby directed to U.S. patent application Ser. No.08/297,200 (D/94226) entitled “Puzzle Cut Seamed Belt”, now U.S. Pat.No. 5,514,436, issued May 7, 1996; U.S. patent application Ser. No.08/297,158 (D/93563) entitled “Puzzle Cut Seamed Belt With StrengthEnhancing Strip”, now continuing U.S. patent application Ser. No.08/522,622, filed Aug. 31, 1995; U.S. patent application Ser. No.08/297,201 (D/94225) entitled “Puzzle Cut Seamed Belt With BondingBetween Adjacent Surface By UV Cured Adhesive”, now U.S. Pat. No.5,487,707, issued Jan. 30, 1996; U.S. patent application Ser. No.08/297,206 (D/94226Q) entitled “Endless Seamed Belt with Low ThicknessDifferential Between the Seam and the Rest of the Belt”, allowed, butnot yet issued; and U.S. patent application Ser. No. 08/297,203(D/94227) entitled “Puzzle Cut Seamed Belt with Bonding Between AdjacentSurfaces”, all commonly assigned to the assignee of the presentinvention and filed on Aug. 29, 1994.

This invention relates generally to a process and apparatus forproducing an endless seamed flexible belt, and more particularlyconcerns forming the ends of the flexible belt in a puzzle cut patternwhich interlock to form a very low profile seam.

Initially, flexible belts were fabricated by taking two ends of a webmaterial and fastening them together by a variety of techniques such assewing, wiring, stapling, providing adhesive joints, etc. While suchjoined or seamed belts are suitable for many applications, such as thedelivery of rotary motion from a source such as a motor, to implement adevice such as a saw blade, they are not as satisfactory in many of themore sophisticated applications of belt technology in common practicetoday. In the technology of the current day, many applications of beltsrequire much more sophisticated qualities and utilities, and inparticular, for such special applications as in electrostatographicimaging apparatus and processes using a flexible photoreceptor belt or aflexible electroreceptor belt, in combination with either a intermediatetransfer member, or image transport devices, or fusing member, ortransfix devices in the flexible belt form. It is ideal to provide aseamless flexible belt whereby there is no seam in the belt whichmechanically interferes with any operation that the belt performs or anyoperation that may be performed on the belt. While this is ideal, themanufacture of seamless belts requires rather sophisticatedmanufacturing processes which are expensive and are particularly moresophisticated, difficult and much more expensive for the larger belts.As a result, various attempts have been made to provide seamed beltswhich can be used in these processes. Previous attempts to manufactureseamed belts have largely relied on belts where the two opposite ends ofa rectangularly cut sheet of the belt material have been lapped oroverlapped and ultrasonically welded to form the seam, or have buttedagainst one another and then fastened mechanically by heat or othermeans of adhesion such as by the use of an adhesive.

The belts formed according to the typical butting technique whilesatisfactory for many purposes are limited in bonding, strength andflexibility because of the limited contact area formed by merely buttingthe two ends of the belt material. Furthermore, belts formed accordingto the lapping or overlapping and ultrasonic welding technique haveexcessive seam thickness which provides a bump or other discontinuity inthe belt surface leading to a significant height differential over theadjacent portions of the belt, of 0.003 inches or more depending on thebelt thickness, which leads to performance failure in many applications.In electrostatographic imaging process utilizing an overlappingultrasonically welded seamed belt, two most severe problems that theimaging belt has encountered during the imaging and cleaning processesare, for example, one involves cleaning the imaging belt of residualtoner after transfer of the toner image due to the excess in seamheight, while the other is the dynamic fatigue seam cracking as a resultof large induced bending stress when seam bends and flexes over variousbelt support rollers of the belt module caused by the increase in seamthickness. Therefore, with a bump, crack or other discontinuity in theseam area of the belt, the cleaning function of a blade is affectedwhich allows toner to pass under the blade and not be effectivelycleaned off from the imaging belt surface, since intimate contactbetween the imaging belt and the cleaning blade is not maintained. Acrack in the seam has also been seen to become a site that collects andtraps toners which are eventually spewed out to the imaging zones of theimaging belt surface causing copy printout defects. Furthermore, seamshaving differential heights may, when subjected to repeated striking bycleaning blades, cause the untransferred, residual toner to be trappedin the irregular surface morphology of the seam. As a consequence, anelectrostatographic imaging belt which is repeatedly subjected to thisstriking action, during imaging and cleaning processes, tends todelaminate at the seam when the seam is subjected to constant batteringby the cleaning blade. Since the severe mechanical interaction betweenthe cleaning blade and the seam also causes blade wear problem, theresult often observed is that both the cleaning life of the blade andthe overall life of the imaging belt under a service environment can begreatly diminished as well as degrading the copy print-out quality. Inaddition, the mechanical striking of the cleaning blade over theexcessive seam height has also been found to give rise to vibrationaldisturbance in imaging development zone which affects the toner imageformation on the belt and degrades resolution and transfer of the tonerimage to a receiving copy sheet. Moreover, the discontinuity or seambump in such a belt may result in inaccurate image registration duringdevelopment, inaccurate belt tracking and overall deterioration ofmotion quality, as a result of the translating vibrations. This isparticularly prevalent in those applications requiring the applicationof multiple color layers of liquid or dry developer on an imaging beltsurface to form the colored toner images, which are subsequentlytransferred to the final receiving copy sheet. Another disadvantage isthat the presence of the discontinuity in belt thickness at the seamarea has also been seen to reduce the flex life and continuity ofstrength of the belt during dynamic fatigue belt cycling when belt bendsover various belt support module rollers.

Therefore, for all practical application purposes and prolonging abelt's service life, it is desired to provide a seam height differentialbetween the seam and the unseamed adjacent portions less than 0.001 inchor not to add more than 20 percent of the unseamed parent materialthickening.

It has been shown that an endless seamed belt, having very small seamheight differential, can be formed with patterned interlocked ends, thepattern of the ends being formed by using a laser or a die to cut thepattern and the patterned cut ends being brought together to interlockto form a seam. In experiments the patterned seams were first generatedusing a CO₂ laser programmed to make various patterned node sizes andspacings. Although the laser was an excellent tool for providing the cutpattern geometries and conditions, however it was a costly and timelyprocess and an inappropriate process for manufacturing seams for largevolumes of belt production implementation because the focused CO₂ laserhas a fine beam size that has to make hundreds of bends, twists, andturns in order to produce the small node pattern cuts as the lasertraverses across the whole wide of the imaging web. Since the CO₂ laseris a heat laser, the generated heat that melts and cuts the imaging webmaterial has been found to cause heat induced material shrinkage of thecut patterns. Alternatively, a 1 inch length punch press die wasdesigned to cut small belt seam samples for testing purposes. The diecut is much faster and cleaner than the CO₂ laser cut and the die cutwas determined to be the preferred method to be used in the patternedseam belt manufacturing process; unfortunately, the mechanical forceemployed for cutting the imaging web is also seen to cause the materialto develop permanent deformation. To yield the desirable seam cutpattern, the size of approximately 0.5mm and the spacings ofapproximately 25 microns for the nodes, it requires very accuratecutting by a die. Such a requirement has been found to be impossible fora die to maintain and provide the demanding tolerances for the width ofan operational belt seam.

In essence, both the CO₂ laser and mechanical die cutting methodologieshave their respective undesirable shortcoming of causing imagingmaterial dimensional change at the vicinity of the cut patterns, whichhave a precise shape tolerance to yield the perfect seam mating result.Therefore, there is an urgent need at present to develop a mechanicallyrobust thin seam design and its preparation method for imaging beltsapplication.

The following disclosures may be relevant to various aspects of thepresent invention:

U.S. Pat. No. 1,303,687

Inventor: C. Leffler

Issued: May 13, 1919

U.S. Pat. No. 2,461,859

Inventor: A. J. Vasselli

Issued: Feb. 15, 1949

U.S. Pat. No. 2,792,318

Inventor: H. P. Welch

Issued: May 14, 1957

U.S. Pat. No. 4,878,985

Inventor: Thomsen et al.

Issued: Nov. 7, 1989

U.S. Pat. No. 5,286,586

Inventor: Foley et al.

Issued: Feb. 15, 1994

U.S. Pat. No. 4,624,126

Inventor: Avila et al.

Issued: Nov. 25, 1986

U.S. Pat. No. 5,688,355

Inventor: Yu

Issued: Nov. 18, 1997

Some relevant portions of the foregoing disclosures may be brieflysummarized as follows:

U.S. Pat. No. 1,303,687 teaches forming a container from a body blankwith the ends dovetailed together and a covering sheet which extendsbeyond the end of the body and has its extending portion secured down,overlapping the dovetail joint to secure and finish the container. Informing the container, the body blank is wrapped around a formingmandrel of the desired shape and the two dovetail ends are interlocked.At the same time the extending ends of the covering sheet, which areprovided with adhesive, are stuck down overlapping the joint.

U.S. Pat. No. 2,461,859 teaches an endless flexible belt with apatterned dovetail joint. A single die cut may cut both ends of thepatterned dovetail joint at the same time. The ends of the belt are cutto form a male and female end with a plurality of spaced dovetailedtabs, the female end fitting into the male end and the dovetailed tabsinterlocking with each other. An adhesive may be used at the belt joint.

U.S. Pat. No. 2,792,318 discloses forming splice joints in fibrousmaterial, each joint being cut so that an interlocking tongue and groovepattern is formed. The tongues and grooves may be different shapes. Inthe finished product, the joints are oriented at a diagonal with respectto the sides. A coating material may be used to maintain the interfittedtongues and grooves, however, it is the interlocking connection of thetongues and grooves that provides the tensile strength of the joint.

U.S. Pat. Nos. 4,878,985 and 5,286,586 disclose fabricating thinflexible endless belts used in electrophotographic printing systems. Thepatents teach overlapping the ends of the belt and welding the endstogether to form an endless belt.

U.S. Pat. No. 4,624,126 teaches a hydraulic press with a cylinderarrangement for equalizing forces in the event of unequal loading of thepress.

U.S. Pat. No. 5,688,355 discloses fabricating a flexible belt byremoving some of the layers on the belt ends by ablation with a maskedexcimer laser beam. The ends are overlapped to form a substantially thinflat surface and fused together to form the endless belt.

U.S. patent application Ser. No. 08/721,418 entitled “Process andApparatus for Producing an endless Seamed Belt” by Schlueter, Jr. etal., filed Sep. 26, 1996 and assigned to the same assignee as thepresent invention, teaches producing an endless flexible belt using apunch and die. The punch and die have patterned edges in the form of apuzzle cut pattern with extremely small nodes and kerfs. The cuttingtolerances of the patterned edges make it necessary to fix the punchwith respect to the die so that there is no misalignment of the punchand die between cutting operations.

All of the above references are herein incorporated by reference.

SUMMARY OF THE INVENTION

To overcome the above shortfalls and provide a mechanically robust thinseam design for flexible belt application, one aspect of the inventionis drawn to a method for producing an endless flexible seamed belt frombelt material stock including positioning a template above the beltmaterial stock and applying a cutting force to the template to form afirst patterned end and a second patterned end on the belt stockmaterial. The cutting force is removed resulting the first and secondpatterned ends of the belt are cut in a puzzle cut pattern with mutuallymating elements which fit together to form a seam when joinedmechanically to enable the endless flexible seamed belt to essentiallyfunction as an endless belt having a substantially uniform thickness.

Another aspect of the invention is drawn to an apparatus for producingan endless flexible seamed belt from belt material stock including atemplate with a puzzle cut pattern formed thereon positioned above thebelt material stock and a cutting force applied to the template to forma first patterned end and a second patterned end on the belt stockmaterial, wherein the first and second patterned ends of the belt arecut in a puzzle cut pattern with mutually mating elements which fittogether to form a seam. When the ends are joined mechanically aflexible seamed belt which essentially functions as an endless belthaving a substantially uniform thickness is formed.

Yet another aspect of the invention is drawn to an endless flexibleseamed belt made by an apparatus including a template with a puzzle cutpattern formed thereon positioned above the belt material stock and acutting force applied to the template to form a first patterned end anda second patterned end on the belt stock material. The first and secondpatterned ends of the belt are cut in a puzzle cut pattern with mutuallymating elements which fit together to form a seam when joinedmechanically to enable the flexible seamed belt to essentially functionas an endless belt having a substantially uniform thickness.

In a manufacturing mode, it is desirable to have a fast and accuratemethod of forming the puzzle cut seam design. Using a template havingthe desired puzzle-cut pattern in combination with an excimer laser forcutting the flexible belt material and creating the pattern is muchquicker and cleaner without the heat induced material deformationproblem as that seen associated with using a CO₂ laser to form thepuzzle cut seam. Alternatively, a template in the form of a punch anddie is also a quick and clean way to cut the flexible belt material.Employing the excimer laser cutting and punch and die cutting arecleaner than the laser cut due to the fact that the CO₂ laser melts thebelt material, which is a particular problem in a multi-layered belt.Having a clean and low profile puzzle cut seam pattern is very importantwhen the belt is used in an electrophotographic machine environment dueto the stringent requirement of very small distances existing betweenthe electrophotographic process subsystem elements and the belt surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features of the present invention will become apparent as thefollowing description proceeds and upon reference to the drawings, inwhich:

FIG. 1 is an isometric representation of the flexible puzzle cut seamedbelt providing a mechanically invisible and substantially equivalentseam in performance to that of a seamless belt.

FIG. 2 is an enlarged view of a puzzle cut pattern used on both joiningends of the belt material to provide interlocking elements having a postportion 14 and a larger head portion 16.

FIG. 3 is illustrative of an alternative configuration wherein male 18,19 and female 21, 23 interlocking portions having curved mating elementsare used in the two ends of the belt material which are joined.

FIG. 4 is a further alternative embodiment wherein the interlockingelements 30, 32 form a dovetail pattern having curved mating elements.

FIG. 5 is an additional alternative embodiment wherein the interlockingrelationship between the puzzle cut pattern on both ends is formed froma plurality of finger joints 22, 26.

FIG. 6 is a greatly exaggerated in scale representation of the seam typegeometry, a very narrow kerf 20, that will be bonded by heat andpressure alone.

FIG. 7 is a greatly exaggerated representation of the belt seam 11 withthe kerf 20 filled with belt compatible material represented by crosshatching.

FIG. 8 is a schematic representation of cutting a rectangular slot at anend of an electrophotographic imaging member web with an excimer laserusing a mask template.

FIG. 9 is a mask template having the desired puzzle cut pattern for theexcimer laser cutting use.

FIG. 10 is a front view of the die press used to form the puzzle cutbelt.

FIG. 11 is an exploded view of the cutting elements in the die press ofFIG. 10.

While the present invention will be described in connection with apreferred embodiment thereof, it will be understood that it is notintended to limit the invention to that specific embodiment. On thecontrary, it is intended to cover all alternatives, modifications, andequivalents as may be included within the spirit and scope of theinvention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

With continued reference to the figures and additional reference to thefollowing description the invention will be described in greater detail.The seam formed according to the present invention is one of enhancedstrength, flexibility and mechanical life which is held together by thegeometric relationship between the ends of the belt material, which arefastened together by a puzzle cut, meaning that the two ends interlockwith one another in the manner of an ordinary puzzle and wherein theseam has voids or a kerf 20 between the surfaces of mutually matingelements, the opposite surfaces of the puzzle cut pattern being joinedtogether to enable the seamed flexible belt to essentially function asan endless belt. The joining of the opposite surfaces of the mutuallymating elements forming the seam may be either a physical joining,chemical joining or some combination of physical and chemical joining.The opposite surfaces of the puzzle cut pattern may alternatively bebound with an adhesive which is physically and chemically compatiblewith the belt material. Typically, this joining provides a bondingbetween the opposite surfaces of the mutual mating elements whichprovides an improved seam quality and smoothness with substantially nothickness differential between the seam and the adjacent portions of thebelt thereby providing enhanced imaging, registration and control asdiscussed above. In this regard, it should be noted that the lower thedifferential in height, the faster that the belt may travel. In anycase, the opposite surfaces of the puzzle cut pattern being joinedtogether are bound with sufficient physical integrity to enable theseamed flexible belt to essentially function as an endless belt. The twoends of the seamed belt may be joined by heating such as by welding,including ultrasonic welding, arc welding and impulse welding, whereintop and bottom elements similar to those that are used to seal plasticbags have two arms which apply pressure and then the elements areheated. In the case of thermoplastic belt materials the thermoplasticnodes may be deformed by heating and may flow into the voids to form orlink together and physically form the bond. As illustrated in FIG. 6 avery narrow kerf between thermoplastic ends of the belt may be filled bythe mere application of heat and pressure. This is like welding the twonodes together. This technique of course is not applicable to thermosetmaterials.

Alternatively the two ends of the belt having the puzzle cut pattern ateach end may be joined by a chemical reaction. This happens in theinstance where the belt material is a thermoplastic and upon heating thethermoplastic at least softens, if not melts, and flows to fill thevoids in the seam.

Another alternative is to apply an adhesive to the voids between themutually mating elements, and in particular, to the opposite surfaces ofthe puzzle cut pattern. With the use of an adhesive a much wider kerfmay be used than the very narrow kerf that may be used for bonding byheat and pressure only thermoplastic materials. This also permits theadhesive to wick into the void or kerf areas. In this regard, theviscosity of the adhesive is important since it's performance depends onit's ability to wick into the voids or the kerf 20 between adjacent cutpieces of the pattern. Accordingly, a relatively high viscosity adhesivewill not perform as satisfactorily as a low viscosity adhesive. Inaddition, the surface energy of the adhesive must be compatible with thematerial from which the belt is fabricated so that it adequately wetsand spreads in the belt seam. As previously described good adhesion isrequired to enable the performance requirements previously discussedwith regard to comparing it to the original material. If the belt ismade of a thermoplastic or thermoset material, it is quite convenient touse thermoplastic or thermoset adhesives which melt and flow at atemperature below that of the belt material but do not soften enough orflow during the belt's operation. The kerf 20, the distance betweenadjacent surfaces of the mutually mating elements of the belt ends canbe built into the belt ends by way of a mechanical die or it can bebuilt into by way of cutting with a laser pattern. If the belt materialis a thermoplastic, a thermoplastic or thermoset or otherwisecrosslinked adhesive may also be used and indeed may be based on thesame material that the belt is fabricated from. However, if the beltmaterial is thermosetting then a thermoplastic or thermoset adhesive maybe used to fill the voids between the opposite surfaces of the puzzlecut pattern. Typically, a hot melt adhesive may be used, which is onethat is solid at room temperature, however, when heated will flow.Typical thermoplastic hot melt adhesives include polyamides, urethanes,polyesters. Typical thermosetting materials include epoxies, polyimides,cyanoacrylates and urethanes. Following bonding, whether it be physical,chemical or by way of adhesive or any combination of the above, althoughit may not be necessary, it may be desirable to apply pressure toflatten the seam to make it as uniform as possible and control anythickness differential.

Referring to FIG. 1, it should be noted that the mechanical interlockingrelationship of the seam 11 is present in a two dimensional plane whenthe belt 10 is on a flat surface, whether it be horizontal or vertical.While the seam is illustrated in FIG. 1 as being perpendicular to thetwo parallel sides of the belt it will be understood that it may beangled or slanted with respect to the parallel sides. This enables anynoise generated in the system to be distributed more uniformly and theforces placed on each mating element or node to be reduced.

The endless flexible seamed belt may be made of any suitable material.Any suitable belt material may be employed. Typical materials include,photoreceptor materials which may be multilayered such as thosedescribed in U.S. Pat. No. 4,265,990, as well as a variety ofthermoplastic and thermosetting belt materials. Typical materialsinclude polyesters, polyurethanes, polyimides, polyvinyl chloride,polyolefins such as polyethylene and polypropylene and polyamides suchas nylon, polycarbonates, acrylics. In addition, elastomeric materialssuch as silicones, fluorocarbons such as Vitons E. I. DuPont™, EPDM andnitrites etc. For certain purposes, metallic; cloth and even paper maybe used. The belt material is selected to have the appropriate physicalcharacteristics for specific utilities such as tensile strength, Young'smodulus, typically 1×103 to 1×106, electroconductivity, typically 10⁸ to10¹¹ ohm cm volume resistivity, thermal conductivity, stability, flexstrength and in certain applications, such as transfix, being capable ofbeing subjected to high temperatures. Other important characteristics ofthe belt material include surface energy desired low for good tonerrelease, for example, gloss, dielectric constant and strength.

The puzzle cut pattern has been formed according to conventional shapingtechnique, such as by die cutting or laser cutting with commerciallyavailable lasers, such as a CO₂ laser or excimer laser. However, the useof excimer laser puzzle pattern cutting is preferred because itgenerates a beam of sufficient width and intensity that within anacceptable time will provide the desired cut. Following cutting by thelaser beam it can be deburred and cleaned by air, ultrasonics orbrushing if necessary. The puzzle cut pattern may be formed on each ofthe ends by a male and female punch with the belt material in betweenwhich punches out the shape. Alternatively, it could be a pattern on awheel which rolls over the material.

It has been found that a CO₂ laser utilizing a focused heat beam isunsuitable for the precise reshaping requirements of this invention.Although a CO2 laser beam can be small and localized, it melts or burnsthe material upon which is focused. Because the wavelength of a CO₂laser is about 10.6 micrometers, which is in the far infrared region ofthe spectrum, the CO₂ laser beam apparently functions much like a heatradiation beam that melts and burns away the material to be removed.This is evidenced by the appearance of smoke rising from thephotoreceptor during CO₂ laser beam treatment. Moreover, the molten massaccumulation forms beads of surface protruberance upon cooling to roomambient. Localized heating caused by a CO₂ laser also tends to distortor warp photoreceptor substrates. In addition, when heat-type laserbeams are utilized, multiple passes are often required to control theremoval of material from both marginal end regions of the imagingmember. These multiple passes require complex equipment and prolong thetime required for material removal. Attempts to use of a YAG laserhaving a wavelength of about 1.06 micrometers to remove material from aphotoreceptor merely heats the photoreceptor and discolors the chargegenerator layer. Lasers that ablate photoreceptor layers by heating alsocauses undesirable ripples to form in the photoreceptor. These ripplestrap toner particles which, in turn, tend to agglomerate and form smearson the photoreceptor surface or form particulate deposits in backgroundareas of final imaged copies. In addition, the ripples trap air which isheated during impulse heat-fuse welding process to the point whereexpansion of the air causes bubbles that weaken the final weldedphotoreceptor seam. The presence of small bubbles (that heat up andexpand during welding) can produce a pronounced weakness in the weldedseam, particularly when the overlap of the sheet ends is relativelysmall.

The puzzle cut ends of the present invention are formed by exposing abelt to a masked excimer laser. Excimer laser has a characteristicrectangular beam profile emission of about 3.0 cm×1.5 cm and exhibits anuniform top hat like energy distribution. Excimer lasers take their namefrom the excited state dimmers from which lasing occurs. Currently, themost important excimer lasers are the rate-gas-halides such as ArF, KrF,XeCI, and XeF which produce intense UV radiation of distinctivewavelengths from 193 nm (ArF), 248 nm (KrF), 308 nm (XeCI), to 351 nm(XeF). Since the excimer molecules have short life-times that exist foronly a few nanoseconds, they require a fast excitation process. Theexcimer lasers, however, have no or only weakly bound ground states andthey imply high gain and high energy capabilities. Thus, in comparisonto solid state lasers, excimer lasers are easier to operate. Incommercial excimer laser technology, the excitation process is executedby a fast high pressure electrical discharge applied to a gas mixturewhich contains small amounts of a halogen and a rate gas, diluted inhelium or neon buffer gas. This results in generation of short UV laserpulses leaving the discharge cavity in a beam of fairly low divergenceand exhibiting a characteristic rectangular profile of approximately 3cm×1.5 cm which has a cross section of about 4.5 cm². No heat isgenerated by an excimer laser and it does not burn the substrate.Therefore, an excimer laser does not heat or otherwise adversely affectareas adjacent the laser path. This permits greater control duringremoval of material. Upon direct exposure, excimer lasers convert thephotoreceptor materials to a gas by breaking down the molecular chainsof polymeric components of the photoreceptor into smaller fragments. Theexcimer laser beam is pulsed during operation. Satisfactory results maybe achieved when the pulse frequency is between about 50 Hz and about500 Hz. Preferred pulse frequency ranges from about 100 Hz to about 300Hz. The frequency of the pulse selected for any given set of sheetmaterials depends upon the speed of traverse, distance and power of thelaser beam. For example, a slower laser beam traverse permits a lowerpulse frequency to achieve the desired removal of belt material to formthe trough. Typical traverse rates for a flexible electrophotographicimaging member sheet are between about 30 mm per second and about 0.5 mmper second.

FIG. 8, represents a moment frozen in time of a first marginal endregion 50 of a multi-layered, flexible electrophotographic imagingmember 52 being traversed, in a direction from right to left, by amasked ultraviolet excimer laser beam 46, which is incident on secondmajor exterior surface 56 along a first edge surface 58 of imagingmember 52. Original excimer laser beam 40 is directed through a metalmasking plate 42 having a rectangular opening 44 which removes the nonuniform low energy edges from beam 40 thereby providing an emergingmasked ultraviolet excimer laser beam 46 of even energy distribution forprecise coating layer material displacement when directed toward secondmajor exterior surface 56. Unlike infrared lasers, such as CO₂ and YAGlasers which produce intense thermal heating effects, exposure ofimaging member 52 to high energy short wavelength UV radiation frommasked ultraviolet excimer laser beam 46 can produce a number ofimportant effects including: energy absorption by long chain polymermolecules to elevate these molecules to an electronic excitation statein the coating layers; chain scission of the polymer molecules intosmall molecular fragments; ablation removal of the molecular fragmentsaway from the surface as a puff of gas, creating a total cutting throughof the material layers adjacent first edge surface 58 of imaging member52. In this manner, each masked excimer laser pulse displaces a thinlayer of material 51 from imaging member 52 to precisely remove imagingmember material in full accordance with the laser beam exposure profileof the mask to yield a predetermined cutting pattern through the imagingmember. The laser beam 40 is pulsed during the imaging member shapingoperation. The frequency of the laser pulses is adjustable from onlyabout a few pulses per second to about 300 Hz. Since each laser pulseoccurs on an extremely brief time scale and provides only the energy formolecular excitation of the polymer coating, no heat is generated in theprocess to cause dimensional distortion or material melting to theimaging member 52. The masked ultraviolet excimer laser beam 46traverses a portion of the imaging member web to create a cut-through55. It is also important that original excimer laser beam 40 is maskedto achieve sharp corners at the top and bottom of cut 55 formed duringexcimer laser ablation.

Any suitable masking plate material may be utilized. A typical maskingplate 42 comprises a metal. Any suitable metal may be utilized. Typicalmetals include, for example, stainless steel, carbon steel, nickel, andthe like. Further, with masked excimer laser beam 46 utilized in theprocess of this invention, no heat is generated and the components ofelectrophotographic imaging member 52 are not degraded by heating orburning. This also avoids heat distortion of areas adjacent the path oflaser beam 46 and achieves greater control of the shape of thecut-through 55 created by masked ultraviolet excimer laser beam 46.Thus, masked ultraviolet excimer laser beam 46 utilized in thisinvention removes coating layers from marginal end region 50 ofelectrophotographic imaging member 52 with greater precision to producethe desired cut-through 55 on electrophotographic imaging member 52.

FIG. 9 shows the mask template 42 with a puzzle cut pattern aperture 44formed therein to be employed for the imaging member cutting applicationdescribed in the preceding FIG. 8. In the embodiment, it is shown thatthe template has a template aperture in the form of a puzzle cutpattern; since the excimer laser emission has an uniform radiationenergy area many times wider than the breadth of the puzzle cut patternaperture in the mask template, the puzzle cut pattern may be easily andquickly generated as the excimer laser is transporting in a straightdirection over the mask template which was positioned directly above andperpendicular to the two edges of an imaging member web. With thiscutting strategy employed for a long imaging member webstock in acontinuous production process, the pattern created at the opposite cutends of a resulting imaging member sheet shall have a perfect matchingmale and female pairs for excellent mechanical interlocking. However, ifdesired this mask template may be split into the left half and the righthalf mask templates for individual creation of left and right endspuzzle cutting in an imaging member sheet.

The mask template of FIG. 9 can also be used to form only one end at atime or be of any desirable pattern to form interlocking ends, dependingupon the configuration of the template. When the pulsing excimer laser40 traverses over the mask template 42 and across the full width of thebelt, a matching pair of puzzle cut ends like that of the templateaperture 44 is created without the introduction of heat.

As may be observed from the drawings, the puzzle cut pattern may takevirtually any form, including that of nodes such as identical post orneck 14 and head or node 16 patterns of male 13 and female 15interlocking portions as illustrated in FIG. 2, or a more mushroom likeshaped pattern having male portions 18 and 19 and female portions 21 and23 as illustrated in FIG. 3 as well as a dovetail pattern as illustratedin FIG. 4. The puzzle cut pattern illustrated in FIG. 5 has a pluralityof male fingers 22 with interlocking teeth 24 and plurality of femalefingers 26 which have recesses 28 to interlock with the teeth 24 whenassembled. It is important that the interlocking elements all havecurved mating elements to reduce the stress concentration between theinterlocking elements and permit them to separate when traveling aroundcurved members such as the rolls 12 of FIG. 1. It has been found thatwith curved mating elements that the stress concentration is lower thanwith square corners where rather than the stress being uniformlydistributed it is concentrated leading to possible failure.

It has been found that with curved mating elements that the stressconcentration is lower than with square corners where rather than thestress being uniformly distributed it is concentrated leading topossible failure. The mechanical bonding, strength and flexibility ofthe bond should be capable of supporting a belt cycling of at least500,000 cycles and the height differential between the seamed portionand the unseamed portion on each side of the seam about 0.001 inch andthe seam have a tensile strength of at least 80% and preferably 90% ofthe parent belt material strength.

The following is a discussion of the interrelationship among the variousbelt and material parameters involved in the mechanical integrity of theseam. The mechanical integrity of the seam was examined and analyzed fora number of configurations and in particular for the preferredconfiguration which involves nodes forming parts of a circle andinterconnecting via a neck on the opposite side. To determine thedeflection under loading conditions, each such node is treated as a beamfixed at the narrowest part of the neck joining the node to the base andthe deflection of each tooth (node and neck) is calculated in terms ofthe orientation of the load relative to the beam. To assure that theseam will not come apart under load, it is imposed that the maximumdeflection of each tooth, when the load, under worse conditions, isnormal to the beam, would not exceed the thickness of the belt itself.Clearly, if the deflection of the tooth is in excess of the thickness ofthe belt then the seam will come apart. Under the above brief analysis,a master relationship connecting a material parameter M typical of theconfiguration with a geometric parameter G such that the belt will notcome apart under loading. $\begin{matrix}{M = \frac{1 - G}{\left( {1 + \sqrt{4 - \frac{1}{G^{2}}}} \right)^{3}}} & (1)\end{matrix}$

In this relationship M is a dimensionless quantity given by$\begin{matrix}{{M = \frac{4{NR}^{3}}{{Et}^{\quad 4}}}{{and}\quad G\quad {represents}\quad {the}\quad {ratio}}} & (2) \\{G = \frac{2R}{w}} & (3)\end{matrix}$

where N is the total load per unit width (i.e. lbs/in.) acting on thebelt, E is the modulus of elasticity of the belt material t, thethickness of the belt, R the radius of the circular node forming theseam, and w is the wave length of one whole period between two adjacentnodes. Equation (1) is a one-to-one relationship between the materialparameter M and the geometric parameter G. Thus, given one of them wecan find the other parameter. Furthermore, because of the dimensionlessnature of these two parameters, a multitude of configurations areembodied in each pair of values satisfying equation (1), by virtue ofthe fact that there is an infinite number of combinations of thevariables involved in that particular pair of values of M and G.Inspection of the geometry of the node shows that the structure ischaracterized by two main features: the shoulder, or that portion wherethere is interference between adjacent teeth, which supports the seam,and the neck of each tooth which represents its strength under loading.The size of the shoulder should be sufficient to insure mechanicalintegrity of the seam without making the neck too small as to weaken itsstrength. Table 1 below lists the various parameters for the identifiedbelt characteristics. While all samples will function as noted above, avalue of G of 0.6 is a good compromise. Many of the samples of courseare impractical to implement relative to factors such as manufacturingease, costs, stress tolerance, etc. Equation (3) shows that G can onlyvary between ½ and 1, the first value refers to the case when theshoulder is zero, and the second value pertains to the case when theneck of the tooth is zero and the node has no strength. Once either M orG is known the entire configuration becomes determinate with the help ofthe above equations and other standard geometric relationships.Measurements on actual belts have generally confirmed the aboveanalysis. To illustrate the solution methodology, suppose a beltmaterial of Young's modulus E=5×105 psi and thickness t=0.004″ issubjected to a tension N=2.0 lb./in. of belt width. H is theperpendicular height between centers of one node or one side of the seamand a node on the other side of the seam. The solution possibilities aregiven in Table 1 below such that the seam will not come apart. If avalue G=0.6 is chosen as a compromise between seam integrity and nodestrength, we find

Node Diameter D = 0.448 mm Period w = 0.747 mm Neck Width g = 0.299 mmNode Height H = 0.69696 G 1/M D W g H .5000 2.000 1.0160 2.0320 1.01601.0160 .5100 5.5296 .7239 1.4194 .6955 .8665 .5200 7.7482 .6469 1.2440.5971 .8246 .5300 9.7913 .5984 1.1290 .5306 .7968 .5400 11.7592 .56291.0424 .4795 .7755 .5500 13.6903 .5351 .9729 .4378 .7580 .5600 15.6054.5122 .9147 .4025 .7429 .5700 17.5179 .4929 .8647 .3718 .7295 .580019.4383 .4761 .8208 .3448 .7174 .5900 21.3751 .4612 .7818 .3205 .7061.6000 23.3363 .4479 .7466 .2986 .6956 .6100 25.3292 .4359 .7146 .2787.6856 .6200 27.3614 .4248 .6852 .2604 .6760 .6300 29.4406 .4146 .6580.2435 .6668 .6400 31.5747 .4050 .6328 .2278 .6578 .6500 33.7722 .3960.6093 .2132 .6491 .6600 36.0424 .3875 .5872 .1996 .6405 .6700 38.3950.3794 .5663 .1869 .6320 .6800 40.8411 .3717 .5466 .1749 .6236 .690043.3927 .3643 .5279 .1637 .6153 .7000 46.0632 .3571 .5101 .1530 .6070.7200 51.8235 .3433 .4769 .1335 .5904 .7300 54.9497 .3367 .4612 .1245.5820 .7400 58.2687 .3302 .4462 .1160 .5736 .7500 61.8060 .3238 .4317.1079 .5651 .7600 65.5913 .3174 .4176 .1002 .5565 .7700 69.6594 .3111.4040 .0929 .5477 .7800 74.0510 .3048 .3908 .0860 .5388 .7900 78.8149.2986 .3779 .0794 .5297 .8000 84.0090 .2923 .3653 .0731 .5204 .810089.7035 .2860 .3530 .0671 .5109 .8200 95.9840 .2796 .3410 .0614 .5012.8300 102.9563 .2731 .3291 .0559 .4911 .8400 110.7522 .2666 .3173 .0508.4807 .8500 119.5388 .2599 .3057 .0459 .4700 .8600 129.5306 .2530 .2942.0412 .4588 .8700 141.0081 .2459 .2827 .0367 .4472 .8800 154.3451 .2386.2712 .0325 .4350 .8900 170.0512 .2311 .2596 .0286 .4222 .9000 188.8397.2231 .2479 .0248 .4086 .9100 211.7410 .2148 .2360 .0212 .3942 .9200240.2999 .2059 .2238 .0179 .3787 .9300 276.9445 .1964 .2112 .0148 .3620.9400 325.7211 .1860 .1979 .0119 .3436 .9500 393.9129 .1746 .1838 .0092.3231 .9600 496.0860 .1617 .1684 .0067 .2997 .9700 666.2290 .1466 .1511.0045 .2722 .9800 1006.3020 .1277 .1303 .0026 .2376 .9900 2026.1140.1012 .1022 .0010 .1885 N, lb/in = 2.0 E, psi = 500000 t, in = .004

To minimize any time out or nonfunctional area of the belt it isdesirable to have the seam width be as narrow as possible. Further, thisenables the seam to be indexed so that it does not participate in beltfunctionality such as the formation and transfer of a toner or developerimage. Typically, the seam is from about 1 mm to about 3 mm wide.

With reference to the embodiment illustrated in FIG. 2, the seam may betypically of the order of one inch wide on a belt which is 16 to 18inches long depending on roll diameter, material modulus or otherparameters and the post and head pattern may be formed from amale/female punch cut with each end being cut separately andsubsequently being joined to form the seam with a roller similar to thatused as a wall paper seamer rolled over the seam by hand to complete theinterlocking nature of the puzzle cut pattern.

The two ends of the belt material are joined by physically placing themtogether in interlocking relationship. This may require the applicationof pressure to properly seat or mate the interlocking elements. Theadhesive material may be the same or it may be different from thematerial from which the belt was fabricated and may be selected fromthose materials previously discussed. Typically, it is a heat sensitivethermoplastic or thermoset material. It may be either chemically, and/orphysically bound to the belt material. The chemical and/or physical bondbetween the adhesive and the belt material may also be formed by theapplication of heat and/or pressure after the adhesive has been appliedIn a particular application impulse welding may be applied wherein heatand pressure are simultaneously applied to at least soften the beltmaterial and the compatible adhesive material 17 (see FIG. 7) so that itfills the kerf and forms an adhesive bond with the belt material. Inthis regard, it is important that the heat applied does not exceed thatwhich would both form the seam and break it by melting it or decomposingit. Other heat sources include conventional heated rolls, a simpleheated iron, ultrasonic welding or a two roll heated nip providing acombination of heat and pressure.

Preferably, the adhesive material applied is of a thickness to provide aquantity of adhesive to fill the kerf spaces between the two sides ofthe puzzle cut seam member. In this regard it should also be noted thatit may be possible to first apply the heat to, the seam of the beltmaterial and the adhesive and subsequently apply pressure while it isstill in a softened condition to force the softened adhesive into kerfor the spaces between the two sides of the puzzle cut seam members. Thepressure applied should be sufficient to fill the kerf and to minimizethe thickness of any bonded joint. While this process clearly provides aphysical bonding between material of the belt seam and the adhesivematerial, it may also provide a chemical bond. A typical example of thiswould be one wherein the belt material is a polyimide and the adhesiveis a polyimide.

Following fabrication, the belt may be finished by way of buffing orsanding and further, may have an overcoating applied, typically, of athickness of 0.001 to 0.003 inch in thickness which can be initiallyapplied to the unseamed belt, the belt seam and the seamed area filledfrom the back of the belt to maintain the uniformity of the functionalsurface. Preferably, and by far the most economical matter is to formthe belt seam initially and then apply the desired overcoating.

The seamed belt according to the present invention may be fabricated inan environmentally acceptable manner in that no solvents are required.The adhesive may be applied to the belt in a suitable manner, such as bybeing applied from a tubular applicator by squeezing or pushing or beingapplied by a spatula. It may be applied on one or both sides of the kerfor voided area and is preferably smoothed on it's surface to provide asmooth surface in the seam area of the belt.

EXAMPLE 1

Using a die cutter, a one inch wide polyimide material was mechanicallycut to provide a radius of the nodes of about 0.5 mm and the center tocenter spacing of about 0.70 mm. The ends of the strip of the one inchwidth polyimide material were then interlocked and rolled with theroller to flatten the seam. A thermoplastic polyamide web material wasplaced on the lower jaw of an impulse welder Vertrod Corp. Model No.24H/HT¼. The previously joined seam was then centered over the webbingmaterial, heat at approximately 350° F. and light pressure were thenapplied to melt the polyamide web material into the seamed area forapproximately 20 seconds. With the seam remaining on the lower jaw ofthe impulse welder, both sides of the seam were then masked withconventional masking tape, a bead of a polyimide adhesive was squeegeedinto the area formed by the masking tape and permitted to flash torelease solvent for about 15 minutes after which the masking is removed.The impulse welder is once again clamped again and the seam receives twocycles of 350° F. heat for 35 seconds. The seam remained in the impulsewelder for 30 seconds before it was removed and postcured at 400° F. for2 hours and then room temperature dwell for at least 12 hours. Fourteen,12 inch long belts were tested in the flex tester and all had flexingcycles exceeding 750,000 with 9 samples exceeding one million cycles. Ofthe nine belts, which flexed for over a million cycles, the test wasdiscontinued without any of the belts failing. The samples were testedin a flex tester using two pounds in loading, 17 inch per second processspeed around the 25 mm drum rollers.

Turning now to FIG. 10, which shows a front view of the die pressassembly used to cut the patterned ends of the belt. Die 102 issupported by die retainer plate 106. Punch 104 is supported over the die102 by punch retainer plate 108 and punch assembly retainer 120. Astripper 114 surrounds the punch 104, there being a very small clearancebetween the punch and stripper. Stripper 114 has a puzzle cut patternwhich is complementary with the punch puzzle cut pattern so that thestripper assists in locating the punch with respect to the die. Thestripper is fixed to die 102 so that a stock gap exists for the beltmaterial 111 to pass between the stripper and die. The stock gap isformed by shims 140 (see FIG. 11) between the stripper and the die. Thestripper 114, die 102 and die retainer plate 106 are fixed together andremain stationary during the belt cutting process.

Timing blocks 112 are mounted to both ends of punch retaining plate 108and are located above stripper 114. Timing blocks 112 cooperate to keepthe punch assembly level; when the first timing block hits stripper 114this causes the punch assembly to level out and when the other timingblock hits the stripper, the direction of punch assembly is reversed(discussed below).

Guide posts 116 pass through punch retainer plate 108 and die retainer106 and assist in keeping all of the punch and die members properlyaligned. Punch return assembly 118 connects the punch retainer plate 108and die retainer 106 and returns the punch to its ready to cut positiononce the cutting force is removed. Punch assembly retainer 120 supportspunch retainer plate 108, punch 104 and timing blocks 112; punchassembly retainer 120, punch plate 108, timing blocks 112 and punch 104being fixed with respect to each other. Punch assembly retainer 120 is asolid piece of metal and distributes the cutting force along the fulllength of punch retaining plate 108.

At the top center of the punch assembly retainer is force receivingsurface 122. Above force receiving surface 122 is force generatingassembly 124 having a force generating surface 126, a cylinder travelgap 128 being formed between the two surfaces when the force generatingassembly is in the retracted position The force generating assembly maybe a hydraulic press or any equivalent press which can generatesufficient force to cut the belt material. Force generating assembly 124provides a downward force with force generating surface 126 contactingforce receiving surface 122 which supplies the cutting force to thepunch assembly until both timing blocks 112 contact stripper 114 (asshown). At this time the force generating assembly force direction isreversed and the cutting force removed. Punch assembly 120 moves upwarddue to the upward force of spring 121 of punch return assembly 118, thetop of the bolt 119 limiting the upward movement of the punch.

Force generating assembly 124 is supported independently of the punchand die members. Force generating assembly horizontal support 130 andvertical supports 132 are attached to die table 140. Vertical supports132 have a foot member 134. Die retainer 106 supports all of the punchmembers and die members and is also attached to die table 140. As shown,die retainer 106 has cut out portions 136 on its underside with footmembers 132 captured in the cut out portions. This configuration insuresthat force generator assembly horizontal support 140 will remainstationary with respect to the die when the cutting force is supplied byforce generating assembly 124.

Rather than having the punch assembly attached to the force generatingmember as is usual for die presses, the punch members are fixed to thedie members by punch return assembly 118. The punch return assembly 118shown has a plurality of punch return assembly bolts 119 and punchreturn assembly springs 121, which connect the punch and die assembliesand bias the punch assembly towards the force generating assembly, awayfrom the die assembly, when the cutting force is removed. Thisconfiguration allows the punch and die to remain in close proximity andproperly aligned with one another. Any misalignment of the punch and diewould result in catastrophic failure when the next punch force isapplied.

An exploded view of the punch and die assemblies is shown in FIG. 11.The cutting assembly 100 is formed of a die 102 and punch 104. The dieand punch have complementary surfaces which form the puzzle cut patternwhen the cutting operation is performed. Die 102 has two die cuttingends 160 and 161 and two die cutting edges 162 and 163 and punch 104 hastwo punch cutting ends 164 and another end(not shown) and two punchcutting edges 166 and another edge (not shown). Die cutting end 160 andpunch cutting end 164 interact to form the puzzle cut pattern at thefirst end of a belt and die cutting end 161 and the other punch cuttingend interact to form a complementary puzzle cut pattern for the secondend of a belt with die cutting edge 162 and punch cutting edge 166interacting to form a first side of the belt and die cutting edge 163and punch cutting edge (not shown) interacting to form a second side ofthe belt. There is a very small clearance between punch cutting edgesand the die cutting edges to insure proper cutting tolerances of beltmaterial 111. A stock gap is formed between stripper 114 and die 102surfaces with shims 142 spacing the two members for the desired stockgap width.

Stripper 114 holds the cut belt material in place as the punch returnsto its pre-cut position, thus performing its stripping function. Inoperation, the die assembly cuts the first end of belt at the same timeit cuts the second end of belt. The belt material is fed through thestock gap in any known manner, for example as a mechanized or handplacement process, the length of the belt being determined by thedistance between the first puzzle cut end and the second puzzle cut endof the punching template.

The first feature that required development in forming the extremelyaccurate punch and die cutting edges was the proper steel and heattreatment process to maintain less than 0.04% dimensional change and nowarpage when wire cut or ground. After several experiments, the optimummaterial and process was D-2 steel, 0.5 inch thick die plates hardenedto R/C 57 and drawn three times at 1875 Fahrenheit. After hardening, theplates were cryogenically treated to −120 Fahrenheit. Then two more drawoperations at 920 F. and 950 F. were performed. A cut relief wasincorporated in the center of the die to relieve stress prior tohardening. The treated material was then cut using an EDM technique, thepunch 104 and die 102 plates being formed separately. Four cuttingpasses were required to maintain tolerances so that the very small nodesand even smaller spacing tolerances required were produced in thefinished punch and die. The last cutting pass was a skimming pass of0.0002 inches. The length of the die depends upon the desired beltwidth. The belt width can be as much as 60 inches using the drawing andEDM cutting techniques outlined above.

EXAMPLE 2

The particular configuration of the puzzle cut with the rounded puzzlecut pattern will be discussed (see FIGS. 7 and 8), however any desiredpattern could be formed with the appropriate punch and die pattern. Theapproximate clearance between the punch and die patterned edges is0.0002 inches, the punch and stripper clearance is 0.0001 inches, theclearances being measured on each side of the punch and die. The nodediameter was 0.5 mm and the kerf dimension was 25 microns. The punchassembly is returned approximately 0.100 inches above the belt materialafter the cut is made. The punch and die cutting edges may be configuredso that the seam is at a slight skew with respect to a 90 degreestraight edge belt, which increases the integrity of the seam. The beltmaterial used may be any material described above, for example aphotoreceptor or Mylar. The length of the puzzle cut pattern punchcutting ends is 18 inches and the distance between punch cutting ends is3 feet. Using the above shapes, tolerances and materials, a “seamless”,i.e. a belt which essentially performs as a seamless belt, puzzle cuttransfer belt was produced.

The above cross referenced patent applications together with the patentscited herein are hereby incorporated by reference in their entirety inthe instant application. It is, therefore, apparent that there has beenprovided in accordance with the present invention, a precision punch anddie and a die press for forming puzzle cut patterned belts that fullysatisfies the aims and advantages hereinbefore set forth. While thisinvention has been described in conjunction with a specific embodimentthereof, it is evident that many alternatives, modifications, andvariations will be apparent to those skilled in the art. Accordingly, itis intended to embrace all such alternatives, modifications andvariations that fall within the spirit and broad scope of the appendedclaims.

We claim:
 1. An apparatus for producing an endless flexible seamed beltfrom belt material stock, the apparatus comprising: a templatepositioned proximate to one side of the belt material stock and a dieassembly positioned proximate to the opposite side of the belt materialstock; a cutting force arranged to be applied to the template tosimultaneously form a first puzzle cut patterned belt end on a first endof the belt material stock and a second puzzle cut patterned belt end ona second end of the belt material stock, the first and second puzzle cutpatterned belt ends comprising mechanically interlocking elements thatare able to mate to form an endless flexible seamed belt, wherein thetemplate is a punch assembly including a punch with a first punchcutting edge having a first puzzle cut punch pattern having a series ofalternating nodes with diameters from about 0.1 mm to about 1.0 mm,wherein the nodes of the first puzzle cut punch pattern form a bodyportion and a neck portion such that the width of the body portion islarger than the width of the neck portion, and a second punch cuttingedge opposite the first punch cutting edge having a second puzzle cutpunch pattern having a series of alternating nodes with diameters fromabout 0.1 mm to about 1.0 mm, wherein the nodes of the second puzzle cutpunch pattern form a body portion and a neck portion such that the widthof the body portion is larger than the width of the neck portion; thedie assembly including a die with a first die cutting edge having afirst puzzle cut die pattern that is complementary to the first puzzlecut punch pattern and a second die cutting edge opposite the first diecutting edge having a second puzzle cut die pattern that iscomplementary to the second puzzle cut punch pattern; wherein thecutting force is generated by a force generating assembly in a cuttingoperation in which the punch and die cut the belt material stock.
 2. Theapparatus of claim 1, further comprising: a force generator surface onthe force generating assembly that transmits the force of the forcegenerating assembly to the punch assembly; a force receiving surface onthe punch assembly for receiving the force of the force generatingassembly; and a gap formed between the force generator surface and theforce receiving surface when the force generating assembly is in aretracted position so that the punch assembly is disconnected from theforce generating assembly.
 3. The apparatus of claim 1, furthercomprising a punch return assembly that resiliently fixes the punchassembly to the die assembly.
 4. The apparatus of claim 3, the punchreturn assembly comprising: at least two bolts connecting the die andpunch assemblies together; and at least two springs, one spring mountedon each bolt, the springs biasing the punch towards the force generatorand the bolts limiting the movement of the punch in the directiontowards the force generator so that a space from about 0.05 inches to0.2 inches is formed between the punch and die when the cutting force isremoved.